Telecommunications networks are required to provide the location of the participants in a call for charging and data retention purposes. For example, the network provider may have location-based charging schemes, or provide location specific services. This information is called Network Provided Location Information (NPLI). When the caller is connected directly to the telecommunications network (i.e. via a basestation/eNodeB of the network), the NPLI is provided by the basestation. Similarly, when the caller is roaming, the NPLI is provided by the roaming network.
When determining location information for a UE connected to a Wireless Local Area Network (WAN), e.g. via Wi-Fi™, which connects to the telecommunications network via an IP link, the NPLI is provided by WAN. This process is currently under standardisation. However, the standards are concerned with the communication within the telecommunications network, and between the telecommunications network and the WAN, and do not consider the handling of NPLI within the wireless access itself.
A further issue affecting WAN access is that it is not currently possible to reserve resources on the WAN, or for the telecommunications network to determine available bandwidth on the WAN. Where the UE is connected directly to the telecommunications network, the network will monitor resource usage and available resources, and reserve resources for the UE when the UE initiates a new session. This ensures that the resource usage in the network does not rise so high that it negatively affects quality of service for all users (though some users may be unable to create sessions if their section of the network is close to capacity, this is considered a better outcome than all users having significantly reduced quality of service).
Such resource management is not possible for a UE connected to a WAN. Firstly, the telecommunications network does not necessarily know the total available resources of the WAN. Secondly, the telecommunications network has no mechanism for reserving resources within the WAN. Thirdly, the WAN may provide service to multiple independent telecommunications networks (e.g. to networks run by different operators), so each telecommunications network does not know the current resource usage in the WAN. Therefore, if a large quantity of traffic is passing through a WAN, the quality of service for all users may degrade well below acceptable levels.
A diagram showing the connections between a telecommunications network and a trusted network is shown in FIG. 1. The PDN Gateway (PDN-GW) connects to the Trusted Wireless Access Gateway (TWAG) via the S2a interface, and the AAA server connects to the Trusted Wireless AAA Proxy (TWAP) via the STa interface (as defined in 3GPP TS 23.402 v12.4.0, “Architecture enhancements for non-3GPP accesses”). The TWAG and TWAP are generally co-located. The TWAP/TWAG handles all communication between the WAN and the telecommunications network, including signalling to the UE and signalling to other nodes of the WAN (e.g. the Wireless Access Control (WAC)).
For untrusted WANs the connection between the PLMN and the UE is as shown in FIG. 2 (excluding the dotted line). An untrusted WAN is a WAN in which at least part of the connection between the UE and the PLMN is untrusted and/or insecure. Communications between the PLMN and the UE are handled by an evolved packet data gateway (ePDG). The ePDG connects to the UE via the wireless access network. Since at least one link between the ePDG and the UE is untrusted, an IPSec tunnel is set up between the ePDG and the UE during registration of the UE with the network. Following registration, the ePDG and the UE communicate via the tunnel, over the SWu interface.